Examples of previously known power drive units are shown in the Flippo U.S. Pat. No. 4,191,094 and Aldrich U.S. Pat. No. 4,210,066, which are owned by the assignee of this application. In the power drive unit, a hydraulic motor is operatively connected to the thrust reverser structure and is in a hydraulic circuit including control valves for causing the motor to operate to either cause a stow or deploy cycle of the thrust reverser structure. In the Flippo patent, the motor has a torque control wherein the displacement of the motor may be varied to modify the torque/speed operation of the motor.
The prior art power drive units have not had an auto-restow valve which reacts to an excessive pressure in the motor discharge line resulting from a high load in an inadvertent deploy cycle to cause a reversal in direction of operation of the motor to return the thrust reverser structure to a stowed position.